Liquid crystal display elements are used in various measuring instruments, automotive panels, word processors, electronic notebooks, printers, computers, television sets, clocks and watches, and advertising boards, as well as clocks and watches and electronic calculators. Typical liquid crystal display modes include twisted nematic (TN), super-twisted nematic (STN), vertical thin-film transistor (TFT), and in-plane switching (IPS) TFT. Liquid crystal compositions for use in such liquid crystal display elements should be insensitive to external stimuli, such as water, air, heat, and light, have a liquid crystal phase in as wide a temperature range as possible around room temperature, have low viscosity, and have a low driving voltage. A liquid crystal composition is composed of several to tens of compounds so as to achieve optimum anisotropy of dielectric constant (Δ∈) or optimum anisotropy of reflective index (Δn) of each display element.
Liquid crystal compositions having negative Δ∈ are used in vertical alignment (VA) displays. Liquid crystal compositions having positive Δ∈ are used in horizontal alignment displays, such as TN, STN, and in-plane switching (IPS) displays. In a drive system reported previously, a liquid crystal composition having positive Δ∈ is vertically aligned in the absence of voltage, and a transverse electric field is applied for display. Thus, there is an increasing demand for liquid crystal compositions having positive Δ∈. There is also a demand for low-voltage drive, high-speed response, and a wide operating temperature range in any drive system. In other words, there is a demand for positive Δ∈ having a large absolute value, low viscosity (η), and a high nematic phase-isotropic liquid phase transition temperature (Tni). In order to set the product Δn×d of Δn and the cell gap (d) at a predetermined value, the Δn of a liquid crystal composition must be adjusted in an appropriate range for the cell gap. Furthermore, because high-speed responsivity is important for liquid crystal display elements for use in television sets, liquid crystal compositions should have low rotational viscosity (γ1).
For example, a liquid crystal composition containing a combination of compounds represented by the following formulae (A-1) to (A-3), which are liquid crystal compounds having positive Δ∈, and a compound represented by the formula (B), which is a liquid crystal compound having neutral Δ∈, is disclosed as a liquid crystal composition designed for high-speed responsivity. It is widely known in the field of liquid crystal compositions that among the characteristics of such a liquid crystal composition, the liquid crystal compound having positive Δ∈ has a —CF2O— structure, and the liquid crystal compound having neutral Δ∈ has an alkenyl group (Patent Literature 1 to Patent Literature 4).

The manner in which liquid crystal display elements are to be used and methods for producing the liquid crystal display elements change with the increasing number of applications of liquid crystal display elements. In order to adapt to such changes, it is necessary to optimize characteristics other than known basic physical properties. More specifically, VA and IPS liquid crystal display elements containing liquid crystal compositions have come to be widely used, and very large, 50-inch or more, display elements are put to practical use. Methods for filling substrates with liquid crystal compositions also change with increases in substrate size. A one drop fill (ODF) method has become the mainstream instead of the known vacuum injection method. However, deterioration in display quality due to drop marks of liquid crystal compositions on substrates has become an issue.
In a process of manufacturing a liquid crystal display element by the ODF method, the amount of liquid crystal composition to be dropped should be optimally adjusted to the size of a liquid crystal display element. When the amount of dropped liquid crystal composition deviates significantly from the optimum amount, this disturbs the balance of the designed refractive index or driving electric field of liquid crystal display elements, thereby causing display defects, such as spots and poor contrast. In particular, the optimum amount of dropped liquid crystal is small in small liquid crystal display elements frequently used in popular smartphones. Thus, it is difficult to control the deviation from the optimum value within a certain range. Thus, in order to maintain high manufacturing yields of liquid crystal display elements, liquid crystal compositions should not be greatly affected by rapid pressure changes in dropping apparatuses or impacts due to dropping of liquid crystal and should be consistently dropped for extended periods.
Thus, liquid crystal compositions for use in active-matrix driven liquid crystal display elements driven in TFT elements should have improved high-speed responsivity, specific resistance, voltage holding ratio, and insensitivity to external stimuli, such as light and heat, of the liquid crystal display elements, while methods for manufacturing the liquid crystal display elements are taken into consideration.